Optimus Prime features in the Transformers: Robot Masters storyline. He leads the Autobots against a dimension-hopping Megatron, who attacks Autobot City in a new Tyrannosaurus rex form. Their clash revolves around the newly discovered energy source, solitarium, which draws Autobots and Decepticons from various timelines into the conflict. The Robot Masters narrative unfolds through pack-in minicomics, brief online mini-comics, and DVDs included with specific toys. Toy releases include RM-01 (G1 Convoy) and RM-10 (a metallic version of G1 Convoy with a DVD). Information within this storyline focuses on Optimus Prime's role in this central conflict.